静态应力扰动对走滑断层阶区附近地震破裂传播影响的二维数值模拟

Two-dimensional Numerical Simulations of Effects of Static Stress Disturbance on Seismic Rupture Propagation near Stepovers of Striking-slip Fault

动态破裂在走滑断裂带上阶区附近的传播能力控制了地震破裂的可能规模,而非均匀应力场对动态破裂的传播有显著影响。在本研究中,我们通过整合动态破裂模型和静态应力扰动模型,构建了走滑断层上的非均匀应力场,对走滑断层阶区附近前次动态破裂所产生的静态应力扰动对后续破裂传播行为的影响进行了二维动态破裂模型研究。模拟结果表明,当考虑到走滑断层上的地震复发行为时,即使前序地震破裂传播被阶区所阻挡,其所产生的静态应力扰动也可显著提升下次地震跨该阶区传播的能力。另外,不同的初始均匀应力使得动态破裂能够跨大致相同宽度的阶区传播。较大的应力降或者较小的断层强度比(S)能够使得动态破裂在相对较宽的阶区上传播。因此,在研究走滑断裂带不同分段的级联破裂模式时,需要考虑前序地震所造成的静态应力扰动影响。

Capability of dynamic rupture propagation along stepover of strike-slip fault controls the possible size of earthquake rupture. The effects of heterogenous initial stress on dynamic rupture propagation are significant. In the study, we integrate a dynamic rupture propagation model with a static stress perturbance model to construct a heterogenous stress field along strike-slip fault. Then, we investigate the influence of static stress perturbance produced by previous rupture on subsequent rupture near stepover along a strike-slip fault. Our two-dimensional numerical results show that static stress perturbance produced by previous rupture improve the capability of rupture propagating across stepover in the subsequent event significantly even the stepover arrested previous rupture. The influence of various high initial stress on rupture propagation across stepover along a strike-slip is insignificant. Rupture with various high initial stress can propagate across stepover of similar width. Larger stress drop and smaller fault strength ration(S) can improve the capability of rupture over stepover with larger width. So, static stress perturbance produced by previous events should not be ignored when studying the cascading rupture behavior along fault segmentations.